Process of lasting box toes in unlined shoes



1955 w. H. HEATON- ET AL 2,714,734

PROCESS OF LASTING BOX TOES IN UNLINED SHOES Filed Feb. 15, 1955 2,714,734 Patented. Aug. 9, 1955 PROCESS OF LASTING BOX TOES IN UNLINED SHOES Walter H. Heaton, Franklin, and Ronald W. Morse, Newton, Mass.

Original application September 8, 1952, Serial No. 308,366. Divided and this application February 15, 1955, Serial No. 488,384

1 Claim. (Cl. 12-445) This invention comprises a new and improved process of lasting box toes of the solvent softening type in unlined shoes.

Solvent softening box toes have been used with entire success for many years in the manufacture of lined shoes where the box is located between the outer integument of the upper and the lining, and the lining is interposed between the box and the last during many of the shoemaking operations to which the shoe is subjected. The solvent softening compounds with which such box toes are impregnated are very highly adhesive and necessarily so because it is important that. the box should be firmly bonded to the lining in order to prevent the lining from sagging and dropping during the life of the shoe.

There is now, however, an insistent demand for some satisfactory procedure by which solvent softening box toes may be used in unlined shoes where the box toe must come in direct contact with the last. The industry has for a long period struggled with the problem of providing a solvent softening box toe adapted for unlined shoes and so constructed and arranged as to prevent adhesive contact between the box and the last during those operations in which the box is conditioned, that is to say, while the box has been rendered soft, pliable and adhesive by solvent treatment. If any trace of the stiffening compound of the box reaches the surface of the last while in this condition, the box sticks to the last so that it is almost impossible to remove the shoe without tearing it to pieces. The process of the present invention prevents that objectionable occurrence.

Many attempts have been made to solve the problem by coating the inner face of the box toe with a nonadhesive shield of rubber, cellophane or wax or a composite layer of such materials, but these attempts have not been successful because such non-adhesive coatings have split or ruptured when the box toe is strained in the pulling over or lasting operations and when this occurs the stiffening compound seeps through the cracks and adheres to the last with disastrous results.

The present invention is based on our discovery that the difficulties heretofore encountered are obviated by incorporating upon the inner face of the box toe a thin layer of polyethylene. This material is highly non-adherent and has a high factor of elastic elongation beside being exceptionally tough in texture. Consequently the polyethylene layer is capable of stretching without danger of rupture even when the box toe is severely strained and distorted while being drawn under pressure against the surface of the last. The polyethylene layer, moreover, is strictly nontoxic and antiseptic when in contact with the wearers foot. It is in itself highly flexible and so does not interfere in the slightest degree with the flexibility of the moistened and conditioned box toe as it is presented for the pulling over or lasting operations.

In successfully completing our invention it was necessary to solve the problem of permanently bonding the polyethylene film or ply to the body of the box toe. Polyethylene, as already noted, is highly non-adhesive but after extensive research it was found that it could be successfully bonded to a felt or textile base by extruding it in thin sheet or film shape at a high temperature, laying it hot upon the fibrous body material, and then immediately subjecting it to pressure and cooling. This procedure results in a secure and permanent bond entirely satisfactory for the purposes of box toe manufacture. This novel box toe is the subject matter of our copending application Ser. No. 308,366, filed September 8, l952, of which the present application is a division.

In carrying out our novel process we employ a box toe blank of the character above described and interpose it between the outer or leather integument of the upper and the wood of the last while the blank is softened and moistened by suitable solvent, and with the thin polyethylene ply in direct contact with the last. The upper,

with the box toe blank, is then pulled over and lasted in this condition and allowed to dry whereby the polyethylene ply is in non-adherent contact with the last and the fibrous ply becomes stiffened and bonded to the outer integument of the upper.

These and other features of the invention will be understood and appreciated from the following description of a preferred manner of carrying out the process as illustrated in the accompanying drawings in which;

Fig. 1 is a view in perspective suggesting the steps of manufacturing the box toe material in sheet form,

Fig. 2 is a view in perspective of a box toe blank showing the polyethylene ply detached at one corner,

Fig. 3 is a corresponding view of the blank as seen from its fibrous side, and

Fig. 4 is a fragmentary view showing the forepart of an upper on the last in partially lasted condition.

For purposes of illustration our improved process is shown as it is carried out with a solvent-softening box toe blank having a base of the character described in U. S. Letters Patent No. 2,036,588 granted April 7, 193 6, on an application of S. P. Lovell. The fibrous base material 10 comprises a porous felt, or a waterlaid felt, or a woven or knitted fabric of single or double ply. For example, in making box toe blanks for typical womens shoes it is appropriate to use as a fibrous base a true felt composed of 20% wool, cotton, and weighing about 4 /2 ozs. per square yard. The base material is impregnated with a solvent softening stifiening material which, for example, may comprise a mixture of nitrocellulose and boric acid as a substantially uniform dispersion which is porous and receptive of nitrocellulose solvents such as acetone, ethyl alcohol, diac'etone alcohol or the like, or mixtures thereof. Using such impregnating composition with the felt above identified, a dried impregnated sheet weighing about 15 /2 ozs. per square yard is produced, that is, a finished sheet containing about 11 ozs. of impregnating solids of which slightly more than one-half is nitrocellulose and slightly less than one-half is. boric acid. The effect of the boric acid is to increase the porosity of the compound, render it substantially fireproof, and improve its capability of being skived. In some cases it may be desirable to add a small percentage of camphor to the stiffening compound to serve as a plasticizing agent.

In Fig. l the polyethylene is represented as being extruded as a thin continuous sheet from the outlet nozzle 12 of an extruding machine provided with a die slit of the proper dimensions to extrude a sheet from 0.001 to 0.002" in thickness at a temperature of 500600 F. Polyethylene may be supplied to the extruding machine in the granular form in which it is available commercially and if desired a coloring ingredient may be added so that the extruded sheet 11 will be tinted or colored and so indicate at once to the operator which side of the box toe is to be located in contact with the last.

As already noted it is important to extrude the polyethylene sheet 11 at a fairly high temperature in order to form a permanent bond with the fibrous base 10. The polyethylene sheet is led from the die slit immediately into contact with the base 10 and then passed between a pair of pressure rollers 13 and 14 which press the two sheets firmly and progressively into contact and at the same time cool the polyethylene. A very firm and permanent bond is formed in this manner and the composite box toe material in sheet form may with little or no delay be wound into a coil 15.

In Fig. 2 is shown a box toe blank as it is dyed out from the sheet material produced in accordance with the procedure of Fig. 1. The blanks are dyed out in the proper box toe shape and size for the unlined shoes in which they are to be incorporated. In Fig. 2 the polyethylene ply 11 is shown as separated from the fibrous base at one corner of the blank. This may be done with the exercise of sufiicient force and care, and in stripping the polyethylene layer in this manner it will be found that the bond is so strong as to cause the polyethylene layer to carry with it the surface layer of fibres from the base 10. This is because the bond between the polyethylene and the fibre base is stronger than the bond between the components of the base itself.

The box toe blank is completed by skiving its transverse edge in an area 16 upon the fibrous base surface of the blank. In the skiving operation the polyethylene ply is not disturbed while the blank is reduced to a feather edge so that it will not show a transverse line across the tip of the finished shoe.

In carrying out our novel process the box toe blank is first conditioned by the application of a suitable solvent such as acetone, ethyl alcohol or the like, and in this operation the blank is rendered soft, pliable and limp so that it may be readily and perfectly moulded in the upper to the last. The moist and adhesive blank is now laid upon the inner surface of the upper with the fibrous base in face to face adhesive contact therewith and the polyethylene ply uppermost. The forepart of the upper with its adherent box toe blank is now pulled over as indicated in Fig. 4 upon the last 20 and secured by pulling over tacks 21 of which one is shown. The upper is then subjected to the toe lasting operation as suggested in Fig. 4 where the near side of the upper is shown as already lasted while the far side remains to be reached. In these operations the polyethylene layer is not only brought into severe frictional engagement with the wood of the last, but very severely stretched and strained. However, throughout all of such treatment the polyethylene layer maintains its integrity and acts as a complete and continuous elastic shield between the body of the box toe and the wood of the last. The result is that while the fibrous surface of the box toe becomes permanently and adhesively bonded to the upper and stiffened in the shape of the last, there is no tendency whatever on the part of the polythylene layer to stick to the wood of the last.

Our invention is useful also in its application to box toe blanks which are distributed in air tight containers to the manufacturer in a state of full or partial condition, that is to say, dampened and softened by solvent and therefore usable more immediately than blanks distributed in a fully dried state. The polyethylene layer applied as above explained remains intact and without impairment to its bond in such conditioned box toe blanks.

While we have referred specifically to one illustrative stiffening compound and to polyethylene as a material for the protective non-adherent ply, it would be within the scope of the invention to employ any equivalent compounds or materials having the same characteristics.

Having thus disclosed our invention and described in detail an illustrative embodiment thereof and a preferred manner of producing it, we claim as new and desire to secure by Letters Patent:

The process of lasting the toes of unlined shoes which comprises providing a box toe stiffener having a fibrous box toe ply impregnated with a composition adapted to be softened by a solvent and having on one face a thin, tough polyethylene ply coextensive with the fibrous ply and permanently bonded thereto, providing an upper assembled on a last, applying a solvent to the stiffener to soften the composition, inserting the stiffener in the assembled shoe upper with the polyethylene layer in position to engage the last, lasting the toe portion of the upper, thus stretching and conforming the polyethylene ply and fibrous ply as a unit directly to the wood of the last while the bond of the polyethylene ply to the fibrous ply is maintained, whereby the polyethylene ply not only forms a protective barrier for the solvent but also provides a protective layer which prevents sticking of the stiffener to the last, then drying the assembled parts on the last, the said polyethylene ply through the medium of the fibrous ply becoming bonded with the outer integument of the upper as a permanent part thereof, and then removing the lasted upper from the last.

References Cited in the file of this patent UNITED STATES PATENTS 749,267 Davis Ian. 12, 1904 1,982,725 Clarke et al Dec. 4, 1934 2,001,032 Lovell May 14, 1935 FOREIGN PATENTS 486,956 Great Britain June 13, 1938 

